Risk of advanced lesions at the first follow-up colonoscopy after polypectomy of diminutive versus small adenomatous polyps of low-grade dysplasia.

BACKGROUND AND AIMS: The current guidelines for surveillance after polypectomy do not distinguish between diminutive (1-5 mm) and small (6-9 mm) polyps with low-grade dysplasia (LGD). We aimed to evaluate the risk for advanced neoplasia on follow-up colonoscopy.

METHODS: We retrospectively analyzed 443 patients whose worst finding at index colonoscopy was polypectomy of 1 to 5 or 6 to 9 mm polyps with LGD and those who underwent a follow-up colonoscopy.

RESULTS: During a mean follow-up of 32.0 months (interquartile range 13-48 months), advanced neoplasia was found in 26 patients (5.9%). Among all included patients (n = 443), advanced neoplasia was found in 13 of 310 patients (4.2%) of the 1- to 5-mm group versus 13 of 133 patients (9.8%) of the 6- to 9-mm group (hazard ratio [HR], 3.49; 95% confidence interval [CI], 1.6-7.6). Among the patients with 1 to 2 polyps resected (n = 313), advanced neoplasia was found in 8 of 231 patients (3.5%) of the 1- to 5-mm group versus 8 of 82 patients (9.8%) of the 6- to 9-mm group (HR 3.97; 95% CI, 1.47-10.7). Among the patients with ≥3 polyps resected (n = 130), advanced neoplasia was found in 5 of 79 patients (6.3%) of the 1- to 5-mm group versus 5 of 51 patients (9.8%) of the 6- to 9-mm group (HR 2.4; 95% CI, 0.7-8.36). Fair bowel preparation also was associated with the risk for advanced neoplasia at follow-up (HR 3.87, 95% CI, 1.70-8.82).

CONCLUSIONS: Our findings suggest that among patients with up to 9-mm adenomatous polyps, a polyp size of 6 to 9 mm, >2 polyps, and fair bowel preparation are associated with advanced neoplasia.